This invention relates generally to drink dispensers, including nursing bottles for infants. More specifically, the present invention relates to drink dispensers which incorporate a collapsible plastic container to hold a fluid in the dispenser, and a means for expelling air from the collapsible bag so that only the liquid remains for drinking. Moreover, the present invention relates to an improved mouthpiece or nipple to facilitate suction withdrawal of liquid from the drink dispenser.
Nursing bottles for infants are generally known in the art and typically comprise a resilient nipple mounted onto a cap or neck ring which is adapted in turn for mounting onto a bottle containing a selected beverage or food product in liquid form for an infant. The resilient nipple comprises a soft and collapsible mouthpiece which is manipulated by the infant with an alternating collapsing and expansion motion in combination with a sucking action to draw the liquid contents of the bottle through a nipple port. Nursing bottles of this standard type must be held in an inverted or substantially inverted position during use, to ensure fluid flow communication of the bottle contents to the resilient nipple. Further, such conventional bottles naturally fill with air as the infant drinks the liquid. In turn, the feeding infant tends to swallow some of the air, causing indigestion.
As an improvement on this long existing configuration, a newer generation of baby nursing bottles consists of a polymeric cylinder into which a collapsible disposable plastic bag can be positioned. The milk, formula or other liquid is then added to the bag rather than to the cylinder or bottle itself. When topped with the appropriate nipple assembly, this arrangement desirably provides a system under which the bag gradually collapses as the infant feeds from the liquid therein. Because the bag collapses, there is a lesser tendency for air to enter it as an infant drinks. It is intended that this system help an infant to swallow less air during feeding than the infant would when feeding from a noncollapsible bottle.
Nevertheless, an air content problem remains with such collapsible bag feeding systems in that during normal filling procedures the collapsible bag cannot be filled completely with liquid. In this regard, such baby nursing bottles initially require that air in the chamber formed by the nipple and the liner cavity be expelled manually prior to the start of feeding. One typical and common method of expelling air is for the user to insert his or her fingers into an open end of a shell body and push on the liner until all of the air is expelled and only liquid remains. While air may be expelled in this manner for a full bottle, as the amount of liquid in the bottle diminishes the liner must be pushed further into the shell from the open lower end of the shell body until the user's fingers can no longer reach the liner to compress the liner and liquid contained therein to expel any captured air.
Another common problem generally associated with flexible liner baby nursing bottles is the reentry of air into the liner after the bottle has been put aside, particularly in an upright position such as might be the case when the baby is being burped or otherwise attended to. The weight of the liquid in the liner tends to pull the liner downward drawing air into the liner through the nipple. Air may also be drawn into the liner when the baby stops sucking for a period of time since the vacuum created by the sucking is removed.
Yet another problem associated with flexible liner baby nursing bottles is that when the fluid is removed, the flexible liner collapses upon itself along its longitudinal axis. This increasingly narrows the space available for fluid to flow to the nipple. Small pockets of fluid can be formed within the collapsing liner which are nearly completely closed off from the fluid flow. A significant amount of sucking is required to remove these pockets of fluid from the collapsed liner. When combined with the air inflow discussed above, such new generations bottles may provide little advantage over older systems.
Further a variety of modified nursing bottles have been proposed to include a length of flexible tubing extending between the bottle and the nursing nipple. The flexible tubing effectively spaces the nipple from the bottle, with a view toward permitting consumption of the bottle contents without requiring the bottle to be held by the infant or by an adult. In some instances, the tubing terminates at the bottle cap and thus requires support means of some type for retaining the bottle in an inverted position during use. In other designs, the tubing extends through the bottle cap to a position near the bottom of the bottle, and it is intended that the bottle contents be withdrawn by suction while the bottle remains in an upright position.
The present applicant has discovered that conventional nursing nipples of a soft and collapsible construction are generally unsatisfactory for use in nursing bottles of the type having an elongated suction delivery tube connected between the nipple and the interior of the bottle. That is, as the resilient nipple is alternately collapsed and expanded in such bottle designs, the liquid within the bottle is primarily displaced back and forth within the delivery tube, with a minimal quantity of the liquid reaching the infant for consumption. It is believed that the natural inclination of the infant to the collapse and expansion of the nipple sufficiently disrupts the suction action applied to the delivery tube, whereby little liquid actually reaches the infant in the absence of a significantly increased suction.
In summary, prior drinking dispensers which incorporate a collapsible plastic bag or flexible liner, while presenting numerous advantages over prior nursing bottles, still have disadvantages in their design which require attention. When the drink dispenser is in an upright position and liquid is in the lower part of the flexible/collapsible bag or liner, the upper part of the liner tends to constrict in diameter making it harder to suck liquid out of the bag. Further, as the plastic collapses, it is difficult to tell how much liquid is left in the fluid dispenser or bottle.
Accordingly, there is a need for a simple, straightforward device and drink dispenser construction that permits all of the air to be expelled from the flexible liner and which overcomes the drawbacks noted above. In particular, a fluid dispenser is needed which permits a user to clearly ascertain how much liquid remains in the dispenser (permitting, by easy calculation, how much has been consumed). Moreover, a novel drink dispenser is needed which permits air to be easily expelled from the liner, accommodates prefilled liners to be sold as a unit with the surrounding dispenser, and allows the user to suck liquid easily and smoothly with the drink dispenser in virtually any orientation. With regard to nursing bottles, a need exists for a fluid dispenser having an elongated flow or delivery tube to accommodate versatile bottle positioning relative to a resilient nipple member, while insuring substantial liquid flow of the liquid to the infant in response to a normal suction action. The present invention fulfills these needs and provides other related advantages.